The invention relates to a method for determining the elongation and/or compression of a self-adhesive sealing profile applied to a body or body part of a vehicle and to a device for implementing the method.
Sealing profiles on vehicles or vehicle parts serve to seal a movable vehicle part such as a vehicle door against the body frame when the movable part is closed.
A method and a device for applying a sealing profile to a vehicle door is known from DE 101 38 781 A1, in which the self-adhesive sealing profile, provided as an endless profile on a roll, is pulled from the roll and, with its adhesive surface facing the door, is rolled onto a line intended to receive it extending around the periphery of the door. The expression “rolled onto” means that the sealing profile is pressed by an application roller progressively along the surface of the vehicle door, following a predefined installation line and thus attached to the door. The advantage of this rolling method is that the entire seal can be applied in a single continuous work step. The attachment is achieved in that the body or the body part and the application roller are moved relative to each other at a certain speed. It doesn't matter whether the vehicle body or the part of the body is moved relative to an application roller mounted in a stationary position or whether the application roller is moved relative to the vehicle body or part of the vehicle body being held in a stationary position.
The sealing profile to be applied is a so-called “self-adhesive” endless sealing profile. On the side facing the application surface, the sealing profile comprises an adhesive surface, in particular in the form of an adhesive tape. The adhesive surface is covered by a protective strip, in particular a protective film, referred to as a “liner”. The protective strip is peeled off shortly before application. As a result, the adhesive surface is exposed.
Depending on the geometry of the body part, in particular on the geometry of the door, the applied sealing profile must comprise a predefined elongation/compression along an application distance of defined length, so that a permanent attachment to the body part is ensured. In the case of complex geometries, the sealing profile can be applied in a single work step along several application distances arranged in succession, wherein the door sealing profile must comprise a different elongation or compression in each of the various application distances.
To bring about effectively the desired elongation or compression of the adhered sealing profile, the sealing profile can be conveyed at an increased or decreased conveying speed in the direction toward the application roller. In addition, by setting the traveling speed of the arm of the robot which either moves the body part along the stationary application roller or the movable application roller along the stationary body part, the relative speed between the application roller and the body part can be effectively influenced in order to bring about an elongation or compression in the sealing profile.
According to the prior art, the elongation and/or compression of the applied sealing profile is measured by means of the so-called “cutting test” as follows (compare FIG. 1):                The sealing profile 1 is applied to a test body part 4 removed from current production.        The applied sealing profile 1 is cut at least at one point, preferably at several points, by means of a sharp knife transversely to the longitudinal dimension.        On both sides of the cut, the sealing profile 1 is peeled away over a length of 100 mm from the surface of the body part to which it has been applied.        The adhesive surfaces of the peeled-away parts of the sealing profile 1 are covered with soft paper 3, so that the peeled-away parts of the door sealing profile cannot stick to the application surface again.        After a relaxation phase of up to 15 minutes, any elongation/compression which may have occurred in the sealing profile 1 becomes visible in that (if elongation has occurred) a gap shows up between the two ends of the peeled-away sealing profile 1 when they are brought together, or (if compression has occurred) the two ends press against each other when the two ends are brought together.        The size 5 of the gap, i.e., of the elongation, is measured with a sliding caliper.        
This known, spot-check-like, destructive measurement of sealing profiles on test doors does not make it possible to exercise complete control over the application method. This results in a lack of detection sharpness between two destructive tests which makes it impossible to exercise complete control. Because test doors must be used for the spot checks, furthermore, not all possible sources of error can be detected. If, for example, the surface of the test door selected for the spot check deviates from the door in the current production process, elongations and/or compressions resulting from these deviations cannot be detected. Finally, the production process is slowed down by the need to interrupt production so that the test doors can be taken from the line for the following measurement of the elongation and/or compression.